1. Field of the Invention
This invention relates to area heaters and more specifically to electric area heaters including a temperature control.
2. Description of the Prior Art
Conventionally, electric area heaters have consisted of a heating element with a thermostat control which regulates the amount of power dissipated by the heater. More sophisticated room heaters include a heating element regulated by a heater control which provides a thermostat function wherein the control measures the ambient temperature and compares this ambient temperature to a user input temperature. If the ambient temperature is below the user input temperature the heater turns on and if the ambient temperature is above the user input temperature the heater turns off. Another version of this thermostat control provides a temperature hysteresis wherein the heater will turn on at a first temperature and turn off at a second higher temperature. When the ambient temperature falls below the second higher temperature, the heater will remain off until the ambient temperature has fallen below the first temperature point. The temperature hysteresis provides a regulated heater output while preventing the heater from frequently turning on and off causing electrical interference.
Recent developments in intergrated circuit technology provide intergrated circuit elements that may be used to regulate a room heater. One disadvantage of intergrated circuits is that they require special low DC voltages. The area heater power source is traditionally 110 V alternating current. Therefore to use intergrated circuits, a step down transformer connected to the 110 V AC circuits, a step down transformer connected to the 110 V AC line is required together with the DC voltage conversion circuit. Alternatively, nontransformer techniques to produce the required DC voltage output have been employed but include bulky power resistors.
It is an object of the present invention to provide a heater including a control apparatus that uses intergrated circuit technology without having a bulky power supply resulting from the use of transformers or large power resistors. Another object of the present invention is to provide a heater with a control circuit that produces a duty cycle output to more effectively regulate the heating of a room. A further object of the present invention is to provide a heater with a control circuit that minimizes the electromagnetic interference.